1. Field of the Invention
The present invention relates to a camera, and more particularly, to an improvement in a film transporting system thereof.
2. Description of the Related Art
In a conventional film transporting system for a camera, the leading end portion of a film, also called a leader portion, extending from a film cartridge, is engaged with a film sprocket or a take-up spool, and the sprocket or the take-up spool is driven to load the film. In this type of film transporting system, a user must set the leading end portion of the film, resulting in a cumbersome operation. In addition, when the leading end portion of the film is set at a wrong position, the film is not properly loaded. A user may erroneously pull out the leading end portion of the film to expose the film, thus wasting the film.
In order to prevent these problems, a new film cartridge is disclosed in U.S. Pat. No. 4,834,306.
FIGS. 19 to 21 show this new film cartridge, in which FIG. 19 is a longitudinal sectional view thereof, FIG. 20 is a cross-sectional view thereof, and FIG. 21 is a side view showing the main part thereof.
This film cartridge comprises a film passing slit 37; a film 34 which has one end fixed to a recessed portion 38a of a film spool 38 and is wound around the film spool 38; a restraint member 39 located coaxially with the film spool 38, with a regulation portion 39a to prevent outward radial movement of an outermost surface of the film 34 and to prevent the outermost surface of the film 34 from coming into contact with an inner wall 35a of a film cartridge 35; a release member 40, arranged by partially deforming the restraint member 39, for continuously releasing the outermost surface of the film 34 from the radial regulation performed by the restraint member 39; and a guide member 41, integrally formed with the release member 40, for guiding a portion of the film 34 which is released from the restraint member 39 to the film passing slit 37. In accordance with the foregoing arrangement, the outward radial movement of the outermost surface of the film 34 caused by loosening of the film 34 upon rotation of the film spool 38 in a film extruding direction brings the outermost surface of film 34 into contact with the restraint member 39 to apply a force to the film 34 in the film extruding direction. Therefore, the film 34 can be fed out from the film cartridge 35.
When the film cartridge 35 of this type (called a thrust type) is used, after it is loaded in a camera, the film spool 38 is rotated by a fork to feed out the film 34 so that the film 34 is kept extruded out of the film cartridge. Then, the film 34 is wound around the film spool of the camera. Thus, the user need not touch the leading end portion of the film 34, which eliminates the above-described conventional drawbacks.
U.S. Pat. No. 4,977,419 discloses a camera in which a film having a magnetic memory portion is used, in which pieces of photographic information, such as a shutter speed, an aperture value, a date, and a title can be recorded on the magnetic memory portion by a magnetic head and the photographic information is read out as needed.
A camera for such a film is proposed in Japanese Patent Application No. 2-200573 which discloses the following embodiment of the camera.
The camera comprises a fork to engage with a film feed spool of a film cartridge, for extruding and rewinding a film; a film take-up spool; a film driving motor; a first gear train for connecting the film driving motor and the fork when the film driving motor rotates in a first rotational direction; a second gear train for connecting the film driving motor and the fork when the film driving motor rotates in a second rotational direction; and a third gear train for connecting the film driving motor and the film take-up spool when the film driving motor rotates in the first rotational direction, wherein the first, second and third gear trains are arranged to have a relationship of "V01=V02&lt;V03", wherein V01 is a rotation speed of the fork driven by the first gear train, i.e., for example, at the time of extruding the film; V02 is a rotation speed of the fork driven by the second gear train, i.e., at the time of rewinding the film; and V03 is a rotation speed of the fork driven by a driving force transmitted through the film from the third gear train, i.e., at the time of winding the film and by a rotation of the film take-up spool.
FIG. 22 shows the major components of the foregoing film transporting system.
Referring to FIG. 22, reference numeral 101 denotes a film transporting motor as a driving source; 102, a pinion; 103, a first idler gear meshing with the pinion 102; 104, a dual gear having a large diameter gear portion 104a which meshes with the first idler gear 103 and a small diameter gear portion 104b which meshes with sun gears 105; 106 and 107, planetary gears which mesh with sun gear 105 and are rotatably attached to arms 108a and 108b of a first lever 108, respectively.
The first lever 108, which is rotatable around a rotation center of the first sun gear 105, the planetary gear 106, and the planetary gear 107 constitute a well-known planetary gear mechanism.
Reference numeral 109 denotes a second idler gear to mesh with either the planetary gear 106 or 107 in response to a rotational direction of the first sun gear 105. More specifically, the planetary gear 106 meshes with the second idler gear 109 when the motor 101 rotates in a forward direction, and the planetary gear 107 meshes with the second idler gear 109 when the motor 101 rotates in a reverse direction.
Reference numeral 110 denotes a third idler gear meshing with the second idler gear 109; 111, a fork gear meshing with the third idler gear 110; 112, a fork to rotate integrally with the fork gear 111, for rotating a feed spool of a film cartridge (not shown) to extrude and rewind the film.
Reference numeral 113 denotes a second sun gear meshing with the pinion 102; 114, a planetary gear meshing with the second sun gear 113; 115, a second lever for rotatably holding the planetary gear 114 while generating a frictional force with the planetary gear 114, and for causing the planetary gear 114 to revolve around the second sun gear 113 in response to a rotational direction of the second sun gear 113, in the same manner as the well-known planetary gear mechanism.
Reference numeral 116 denotes a spool gear to mesh with the planetary gear 114 only when the motor 101 rotates in the forward direction; 117, a film take-up spool fixed to the spool gear 116 and moving integrally with the spool gear 116; 118, a stopper provided on an unillustrated camera body and located at a position where the second lever 115 can abut against the stopper 118, to limit a range in which the second lever 115 can rotate.
FIG. 23 is a plan view of the gear train shown in FIG. 22 at the time of winding the film around the take-up spool 117. FIG. 24 is a plan view of the gear train shown in FIG. 22 at the time of rewinding the film into the film cartridge (not shown). In FIGS. 23 and 24, the respective gears are rotated in the directions of the arrows.
The camera, which uses the film with the magnetic memory portion, writes a shutter speed, an aperture value, the film speed, etc., to the magnetic memory portion of the film by means of the magnetic head or reads out this information as needed. A failure in reading the information from the magnetic memory portion of the film can be caused by noise, etc. In this case, the camera must again perform the action of reading the information from the same frame of the film. However, the aforementioned camera has the following problem because of the arrangement "V01=V02&lt;V03".
In a film transporting system as shown in FIG. 23, the film is wound around the film take-up spool 117 by one frame. If reading of the information to be performed during this operation is not satisfactorily accomplished, the motor 101 is caused to rotate in the reverse direction. Such a gear train as shown in FIG. 24, is formed to rewind the film to the previous frame. Then, motor 101 is caused to rotate in the forward direction again, and reading of the information is performed again while the film is winding by one frame.
However, if when the motor 101 is changed over from the reverse direction to the forward direction, the second sun gear 113 is rotated to cause the planetary gear 114 to revolve and to mesh with the spool gear 116 before the first sun gear 105 is rotated reversely to cause the planetary gear 107 to revolve and to release meshing with the second idler gear 109. The second idler gear 109 may bite the planetary gear 107. This happens where a revolutionary extent or range of the planetary gear 114 is small.
This is because for the relationship of "V01=V02&lt;V03", a speed of the second idler gear 109 driven through the film taken up by the rotation of the film take-up spool 117, the fork 112 rotated by the film, the fork gear 111 and the third idler gear 110, is faster than a speed at which meshing between the second idler 109 and the planetary gear 107 is released by the planetary gear 107 revolved by the rotation of the first sun gear 105 (from the state shown in FIG. 24 to the state shown in FIG. 23).
In other words, if the planetary gear 107 has not yet completely revolved when the film take-up operation is started, the planetary gear 107 is bitten or caught between the second idler gear 109 and the first sun gear 105 because the rotation speed of the first sun gear 105 (V01) is slower than the rotation speed of the second idler gear 109 (V03).